首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   287624篇
  免费   3369篇
  国内免费   957篇
化学   153692篇
晶体学   4859篇
力学   11831篇
综合类   7篇
数学   32430篇
物理学   89131篇
  2019年   2221篇
  2018年   2645篇
  2017年   2663篇
  2016年   4467篇
  2015年   2919篇
  2014年   4450篇
  2013年   12399篇
  2012年   8979篇
  2011年   11059篇
  2010年   7665篇
  2009年   7414篇
  2008年   10204篇
  2007年   10117篇
  2006年   9795篇
  2005年   9081篇
  2004年   8336篇
  2003年   7473篇
  2002年   7282篇
  2001年   8223篇
  2000年   6243篇
  1999年   4956篇
  1998年   4180篇
  1997年   4110篇
  1996年   3944篇
  1995年   3744篇
  1994年   3548篇
  1993年   3471篇
  1992年   3931篇
  1991年   3860篇
  1990年   3719篇
  1989年   3663篇
  1988年   3680篇
  1987年   3704篇
  1986年   3478篇
  1985年   4629篇
  1984年   4838篇
  1983年   4125篇
  1982年   4544篇
  1981年   4220篇
  1980年   4252篇
  1979年   4379篇
  1978年   4520篇
  1977年   4365篇
  1976年   4402篇
  1975年   4266篇
  1974年   4118篇
  1973年   4451篇
  1972年   2831篇
  1971年   2275篇
  1968年   2226篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Van’kov  A. B.  Kukushkin  I. V. 《JETP Letters》2021,113(2):102-114
JETP Letters - Extraordinary multiparticle effects in quantizing magnetic fields that are manifested in strongly interacting two-dimensional electron systems in MgZnO/ZnO heterostructures have been...  相似文献   
12.
Algebra and Logic - Unary functions definable in o-stable ordered groups of nonvaluational type are studied. Such functions are proved to be piecewise monotone and continuous.  相似文献   
13.
Chen  C. Y.  Kao  C. L.  Huang  S. T.  Kuo  C. E.  Song  P. L.  Li  W. J.  Hsu  L. T.  Li  H. T. 《Chemistry of Natural Compounds》2022,58(1):107-109
Chemistry of Natural Compounds -  相似文献   
14.
Ferrarini  A.  Finotello  A.  Salsano  G.  Auricchio  F.  Palombo  D.  Spinella  G.  Pane  B.  Conti  M. 《Acta Mechanica Sinica》2021,37(7):1192-1192
Acta Mechanica Sinica - A Correction to this paper has been published: https://doi.org/10.1007/s10409-021-01066-2  相似文献   
15.
Li  Y.  Shi  W. H.  Dong  L. M.  Xu  S. X.  Huang  H. J.  Yin  J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,...  相似文献   
16.
Herein, we report a Mott-Schottky catalyst by entrapping cobalt nanoparticles inside the N-doped graphene shell (Co@NC). The Co@NC delivered excellent oxygen evolution activity with an overpotential of merely 248 mV at a current density of 10 mA cm–2 with promising long-term stability. The importance of Co encapsulated in NC has further been demonstrated by synthesizing Co nanoparticles without NC shell. The synergy between the hexagonal close-packed (hcp) and face-centered cubic (fcc) Co plays a major role to improve the OER activity, whereas the NC shell optimizes the electronic structure, improves the electron conductivity, and offers a large number of active sites in Co@NC. The density functional theory calculations have revealed that the hcp Co has a dominant role in the surface reaction of electrocatalytic oxygen evolution, whereas the fcc phase induces the built-in electric field at the interfaces with N-doped graphene to accelerate the H+ ion transport.  相似文献   
17.
Chen  R. J.  Chen  W.  Kong  F. L. 《Analysis Mathematica》2022,48(1):19-28

Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.

  相似文献   
18.
Journal of Mathematical Chemistry - The analytical solutions of an asymmetric double well potential $$V(x)=a\, x^2-b\, x^3+c\, x^4$$ are found to be a triconfluent Heun function $$H_{T}(\alpha ,...  相似文献   
19.
Journal of Applied and Industrial Mathematics - We study the problem of optimal location of the ambulance fleet at the base stations. The objective is to minimize the average waiting time for...  相似文献   
20.
A liquid dewetting method for the determination of the viscoelastic properties of ultrathin polymer films has been extended to study thickness effects on the properties of ultrathin polycarbonate (PC) films. PC films with film thicknesses ranging from 4 to 299 nm were placed on glycerol at temperatures from below the macroscopic glass transition temperature (Tg) to above it with the dewetting responses being monitored. It is found that the isothermal creep results for films of the same thickness, but dewetted at different temperatures can be superposed into one master curve, which is consistent with the fact of PC being a thermorheologically simple material. Furthermore, the results show that the Tg of PC thin films is thickness dependent, but the dependence is weaker than the results for freely standing films and similar to literature data for PC films supported on rigid substrates. It was also found that the rubbery plateau region for the PC films stiffens dramatically, but still less than what has been observed for freely standing polycarbonate films. The rubbery stiffening is discussed in terms of a recently reported model that relates macroscopic segmental dynamics with the stiffening. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1559–1566  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号